* record.xsl: added
This only support unnamed slots.
* record.xspec: added
Notice the documentation style: all sentences and clauses of compound
sentences are on their own lines, indented relative to their parent. This
produces much better diffs when things change.
The submodule is inconvenient and requires awkward project updates for
changes that might be frequent (as it is developed alongside this project).
If we become worried about BC breaks, then we'll do a version check.